A lot of questions I have about worldbuilding, it seems to me, could be asked at History.SE or Physics.SE. Already we have some examples:
How quickly and accurately did news travel in rural medieval Europe? – should this be History.SE?
Are geographically typed planets realistic? – should this be Physics.SE?
I have nothing against these particular example questions; in fact, I've upvoted both. And I can think of many more examples myself; I have yet to actually ask a question because I'm not sure where to draw this line. I think Worldbuilding.SE is the place for at least some of them.
But I also think some of these sorts of questions should be asked on Physics.SE or History.SE. But I'm not sure which ones. I'm not sure about the two I've linked. I was hoping we could get some ideas on how to draw lines.
In particular, active members at History.SE or Physics.SE, it would be great for you to weigh in on the kinds of questions that are not welcome on those sites that we might want to provide a home for.